Refinishing tool for tapped hole and seat



Aug. 9, 1960 J. H. BORLAND REFINISHING TOOL FOR TAPPED HOLE AND SEAT Filed May 28, 1957 INVENTOR. JAMES H. BORLAND ATTORNEY United tates Patent REFINISHING TOOL FOR TAPPED HOLE AND SEAT James H. Borland, Smithfield, R.I. (64 Eagle St., Providence, RI.)

My present invention relates to a hand tool and more particularly to a tool for refinishing a tapped hole and seat.

The principal object of the present invention is to provide a combination tool which will serve to refinish or clean a threaded hole and at the same time clean and refurbish the seat at the top of the hole.

A further object of the present invention is to provide a combination tool of the type described which is particularly adaptable for cleaning and refinishing spark plug holes and seats in internal combustion engines.

Another object of the present invention is to provide a tool which will exert an even cutting pressure on the seat resulting in a smooth finish Without chatter marks.

A further object of the present invention is to provide a tool which will permit the clearing of loose particles from the seat without the danger of having them drop into the threaded hole.

A further object of the present invention is to pro vide a combination refinishing tool for a threaded hole and seat which is simple in construction and easy and economical to manufacture and assemble.

With the above and other objects and advantageous features in view, my invention consists of a novel arrangement of parts, more fully disclosed in the detailed description following, in conjunction with the accompanying drawings, and more particularly defined in the appended claim.

In the drawings,

Fig. 1 is a side elevation of the tool of the present invention extending through a motor head shown in section.

Fig. 2 is a view similar to Fig. 1, but partly in section showing the reaming action.

Fig. 3 is a bottom view of the tool.

Fig. 4 is a section taken on line 44 on Fig. 1.

Fig. 5 is a section taken on line 5-5 on Fig. 4.

It often becomes necessary to clean and refinish a threaded hole and to clean the seat at the top of the hole. For example, it has been found desirable to increase the length of the spark plug mounted in the motor head. It will be found that the last three or four threads of the spark plug o'pening are covered with carbon, and in many cases the seat is also greasy and covered with carbon. It is therefore necessary to insert a tool into the spark plug opening to clear the threads and to clean the seat by hand. It will be found almost impossible to face the seat by hand without leaving a mark because of the uneven pressure exerted by the operator.

The present invention is designed to provide a simple and efficient tool which will serve to clean the threaded opening and simultaneously face the seat with an even constant pressure. For purposes of illustration the tool is shown applied to a spark plug opening in a motor head. Unless the head is removed from the engine the additional problem of disposing of the carbon and dirt particles must be met.

The tool of the present inven- 2,948,000 Patented Aug. 9, 1960 2 tion is designed to permit the removal of the carbon and dirt without fouling the engine.

-Referring more in detail to the drawings, the cylinder head 10 is normally provided with a spark plug well 11 having a central threaded opening 12. A seat 13 is formed at the upper end of the opening 12 to permit the spark plug to tightly seal the opening. The combination tool of the present invention comprises a vertical shaft 14 having a lower wide portion 15 and an upper narrower portion 16, the lower portion terminating in an abrupt shoulder 17. The lower portion 15 is pro'vided with cutting or cleaning threads 18 of a size corresponding to the threads in the opening 12. The threads 18 extend to a point short of the bottom of the portion 15 leaving an unthreaded end 19 which serves as a pilot to center the tool as it is being inserted by hand. The external diameter of the pilot portion 19 should be equal to the mino'r diameter of the threaded opening 12. The lower end of the portion 15 is provided with flutings 20 on four sides to provide the cleaning action. It should be noted that the fiutings 20 extend from the bottom end upwardly approximately half the threaded po'rtion 18. The upper ends of the threads 18 are therefore unfluted. The threads 18 terminate short of the shoulders 17 leaving a wide portion unthreaded. The diameter of this unthreaded portion is equal or greater than the major diameter of the threaded opening 12. p p

The facing tool comprises a collar '21 having an internal diameter equal to the diameter of the lower portion 15. The bottom edge of the collar 21 is provided with teeth 22 cut at a negative angle. The upper internal portion of the collar 21 is provided with a restricted po'rtion having a shoulder 23. The collar 22 is provided with an internal slot or keyway 24 and a pin 25 extends transversely through the narrow portion 16 into the keyway. This permits vertical sliding movement of the 001* lar 21 but locks the collar 21 so that it will rotate with the tool.

The upper narrower portion 16 of the shaft 14 is surrounded by a coil spring 26 having its bottom end resting on the collar 21 and its upper end abutting a hexago'nal head 27 which is mounted on the top of the shaft and locked in place by a transverse pin 28. The spring 26 pushes the collar 21 downwardly until the shoulder 23 rests on the shoulder 17 of the portion 15. As can be seen in Fig. 4, the collar is of such width that it will extend over three or four of the threads 18 in its lowermost position.

In use, the tool is inserted in the thread-ed opening 12 of the head 10 as shown in Fig. 1. It will be found that the pilot end 19 will permit an easy engagement of the threads and the proper centering of the tool. Turning movement of the head 27 will gradually bring the tool do'wnwardly into the position shown in Fig. l. The fluted end 20 will clean the threads completely through the opening 12. If desired the flutes can be packed with oil or grease so that the carbon particles will collect in and stick to the flutes 20. At this point the teeth 22 of the collar 21 will rest on the seat 13. As the tool is turned for further movement as shown in Fig. 2, the teeth will scrape and face the seat 13 under the pressure of the spring 26. As the tool continues through the opening 12 the collar 21 will ride upwardly along its keyway 24 continuing its cleaning action with every turn. When the top of the threads 18 are reached and the unthreaded Wide portion reaches the opening the tool will stop as no further turning action is possible. At this point the tool is reversed and drawn upwardly into the position shown in Fig. 1. As the tool comes up the spring 26'co'ntinues to exert pressure on the collar 21 so that the cleaning action of the teeth 22 continues. The seat is therefore faced both in the forward and reverse movements. There is now an accumulation of carbon and dirt particles is the well -11. The tool is now given two or three reverse turns to lift the collar 21 from the seat 13; It will be noted that at this point the flutes 20 had not yet reached thetop of the opening 12, and the opening 12 is still sealed by the unfluted portion of the threads. .The accumulated dirt can safely be blown out with compressed air and the carbon and dirt will not be blown back through the opening 12. The tool can then be removed.

The lightly loaded spring 26 coupled with the negative angles of the collar teeth 22 permit a constant even pressure in both forward and reverse and insures a smooth seat free of chatter marks. The tool permits the cleaning of the hole and seat and the removal of the carbon and dirt without blowing or pushing them back into the engine.

The teeth 22 have been illustrated as square to clean a flat seat 13. However, the teeth can be shaped to conform to any other shape of spark plug seat. For example, some spark plugs have a beveled seat and some even arcuate seats. The teeth 22 can easily be shaped to conform to any of these. It should be noted that while the collar 21 has a lower stop position formed by the shoulders 23 and 17, it is imperative that there be no upper stop position as this would jam the teeth against the seat and cause chatter marks. The unthreaded portion of the shaft therefore forms the stop and the collar is always free to ride upwardly against the action of the spring. Other advantages of the present invention will be readily apparent to a perso'n skilled in the art.

I claim:

A combination tapped hole and seat refinishing tool comprising a shank, an enlarged head mounted at the upper end of said shank, said shank having a wider lower portion equal to the major diameter of the hole being refinished and terminating in an abrupt shoulder at its upper end, means integral with the lower portion of said shank for cleaning a tapped hole, said means comprising external threads on said lower portion and a plurality of flutings extending upwardly from the bottom end to a point midway of said threads, and means slidably mounted on said shank for scraping the seat around said hole, the lower tip of said shank fo'rming an unthreaded pilot equal in diameter to the minor diameter of said tapped hole, said scraping means including a collar slidably mounted on said shank, said collar having a vertical keyway in the inner surface thereof, a pin mounted transversely through said shank above said threaded portion and extending into said keyway, said collar having cutting teeth on its bottom edge and a coil spring surroundingthe upper end of said shank, the upper end of said coil spring bearing against said enlarged head and the lower end of said coil spring bearing on the upper end of said collar, said collar extending over the upper end of said threads above said fiutings and having an internal shoulder bearing against said' lower portion abrupt shoulder, to form a lower stop element for 'said collar, said collar being vertically slidable on said shank to raise the bottom edge of said collar above the upper end of said external threads.

References Cited in the file of this patent UNITED STATES PATENTS 

